Mineral material, for example rock, is gained from the earth for processing by exploding or excavating. The rock can also be natural rock and gravel or construction waste. Mobile crushers and stationary crushing applications are used in crushing. An excavator or wheeled loader loads the material to be crushed into the crusher's feed hopper from where the material to be crushed may fall in a crushing chamber of a crusher or a feeder moves the rock material towards the crusher. The mineral material to be crushed may also be recyclable material such as concrete, bricks, or asphalt.
Jaw crushers are suitable for example to coarse crushing at quarries or crushing of construction material. According to the function principle of the jaw crusher the crushing takes place against jaws, the so called fixed and movable jaws.
WO 2013/004889 A1 shows a known jaw crusher 100 according to FIG. 1. The frame 10 of the jaw crusher is formed of a front end 101 and a rear end 101′ and side plates. A fixed jaw 102 receiving the crushing forces is fixed to the front end of the jaw crusher. A movable jaw 103 is fixed to a pitman, an eccentric movement of the movable jaw being generated by rotating an eccentric shaft. The jaw crusher comprises further a pulley 104, V-belts 107, a motor 105 and a motor pulley 106 to move the movable jaw 103. The rock material is crushed between the jaws and proceeds after the crushing to further processing for example along a belt conveyor. The crusher further comprises fixing devices 210, 220 to fix the crusher 100 to body structures 121 of a processing plant.
Sandwich type rubber dampers are fixed to the body structures the rubber damper being fixed between two steel plates. The fixing devices 210 of the front end 101 of the jaw crusher are fixed to the sandwich type rubber dampers, and the fixing devices 220 of the rear end rest on the rubber dampers with a friction joint. Only the front end fixing devices 210 are fixed in place to the body structures 121 of the processing plant holding the crusher in place. The friction joint of the rear end 101′ allows the frame of the crusher move if necessary, if a flexibility reserve of the front and rear ends comes to an end in some cases.
The crushing forces and the material dropping into the throat of the crusher cause loads in the crusher, the loads spreading through the crusher frame to the surrounding structures. The dropping of a large stone arriving into the throat and the crushing of the stone causes large forces in the machine direction.
In case of a movable processing plant, particularly equipped with a track base, the fixing devices are subjected to even larger stresses. For example when a crushing plant moves on an uneven terrain the known fixing method causes forces which stress the frame structures of the crusher. The crushing plant may be in a so called cross hanging because of the unevenness of the terrain wherein the body of the crushing plant twists downwards at crosswise located corners. In that situation the fixing devices in said corners are subjected to large vertical stresses which also can lead to breaking of for example bolts, rubber dampers, or welding seams of the supports.
A vertical flexibility of the existing fixing method is small. The fixing method requires straightness and rigidity that the frame of the crusher would not twist according to the base. The twisting of the crusher frame causes misalignment between the pitman and the frame which shortens life of the toggle plate and bearings of the jaw crusher. The accuracy required of the body of the processing plant increases manufacturing costs. Additionally, for example the body of a mobile crushing plant must be positioned precisely before the crushing.
FIG. 2a shows a situation of the rear supports 220 of the jaw crusher when the base 121 of the crusher is straight. An equal force F/2 is directed to both rear supports so that the frame 10 of the crusher is not subjected to any twisting force. FIG. 2b shows the situation of the rear supports 220 of the jaw crusher when an error of the base is s. Then a force ¾ F is directed to a first rear support and a force ¼ F is directed to a second rear support, and the frame 10 of the crusher is subjected to a twisting force. FIG. 2c shows a problematic situation of the rear supports 220 of the jaw crusher when the error of the base exceeds the twisting of the crusher frame 10 being 2s. A force F is directed to the first rear support 220, the force directed to the second rear support is zero, and the second rear support is off the base and does not support the crusher. In that situation the crusher frame 10 is subjected to a maximum twisting force. The situations shown in FIGS. 2b and 2c are undesired in view of the crusher operation.
An object of the invention is to avoid problems present in connection with prior art and/or provide new technical alternatives.